Indexing means



March 3,1942. I w, L, CARLSON 5 2,275,284

INDEXING MEANS Filed Aug. 14, 1940 Z'Sheets-Sheet 1 3maentor lttomeg W. L. CARLSON INDEXING MEANS March 3, 1942.

Filed -Aug. 14, 1940 .2 Sheets-Sheet 2 Gttomeg Patented Mar. 3, 1942 INDEXING MEANS Wendell L. Carlson, Haddonfield, N. J assignor to Radio Corporation of America, a corporation of Delaware Application August 14, 1940, Serial No. 352,509

8 Claims.

This invention relates to methods and means for achieving the rapid and accurate setting of a dial, such, for example, as the tuning dial of a radio set.

The prior art is replete with indexing mechanisms comprising a pawl and a main or auxiliary dial plate provided with detents or notches which are individual to the more frequently dialed settings, and which are selectively engaged by the pawl when the desired setting is achieved. Thus, the dial may be moved rapidly over the pawl to the approximate setting desired whereupon the pawl engages the detent individual to that setting and the operator is advised by his sense of touch that an exact setting has been achieved.

The principal objection to the indexing mechanisms of the prior art is that they either require at least partialdisassembly of the radio or other apparatus during the setting-up process or are otherwise so complicated in their adjustment as to inhibit their use by an unskilled operator. As to the above, see by way of example, Wireless World (British) February 9, 1927, page 162; see also U. S. Patent 1,964,449 to W. L. Carlson.

Accordingly, the principal object of the present invention is to provide a simple, inexpensive and trouble-free indexing mechanism for radio tuners and the like and one which lends itself readily to accurate permanent adjustment by an unskilled operator without disassembly of any part thereof and without danger of impairing previous setups.

The foregoing and other objects are achieved in accordance with the invention by the provision of a dial plate constituted of a relatively soft metal, such, for example, as copper, brass or the like, and by making the detents or notches individual to the several settings therein as by a punch, thrust, or other force applied to the said soft metal plate, preferably from the front of the set, without removing it from the tuning control or other shaft upon which it is mounted. In accordance with the invention, the instrument by which the dial plate is notched may comprise the pawl of the indexing mechanism.

Other objects and advantages together with certain details of construction will be apparent and the invention itself will be best understood by reference to the following specification and to the accompanying drawings, wherein:

Figure 1 is a front elevational view of a radio tuning unit with the control panel broken away to reveal an indexing device constructed in accordance with the principle of the invention,

Figure 2 is a fragmentary plan view of the device of Fig. 1 showing the detent forming element in operation,

Figure 3 is a sectional View taken on the line 3-3 of Fig. 1,

Figure 4 is a front plan view of a radio tuner showing another embodiment of the invention,

Figure 5 is a sectional view taken on the line 5-5 of Fig. 4, and

Figure 6 is a schematic view showing the invention applied to a so-called permeability tuning system.

In the embodiment of the invention shown in Figs. 1, 2 and 3, I designate the front surface and 3 a shelf or base comprising the chassis of a radio set having a control panel 5. A tuning condenser I, mounted on the base 3, has a main shaft 9 which is susceptible of rotation under the control of aknob II which is afiixed to its outer end adjacent the front of the control panel 5. Fixed to the main tuning shaft 9 as by means of a collar I3 is a disc I5 at least the lower half of which is constituted, in accordance with the invention, of copper, brass or other relatively soft and easily deformable material.

Immovably mounted in front of the disc or plate l5, as in an escutcheon I! on the control panel 5, is a dial face I!) which may be provided with radially extending slots 2| or other means in which station markings 23, or other indicia may be inserted. The scale markings 23 may be read in conjunction with a pointer 25 on the control knob ll. Alternatively, the dial face I9 may be fixed on the disc l5 for rotation therewith, in which case a fixed pointer (not shown) may be provided on the control panel 5 or on the escutcheon ll. If desired, the lower half of the dial face l9 may be calibrated in terms of frequency or wave length.

A weighted spring-actuated wedge or V-shape element 21 is mounted adjacent the periphery of the soft metal disc l5 for forming therein the notches or detents 29 which are individual to the more frequently dialed stations. The wedge shaped element 21 is formed of a relatively harder metal than the disc l5 and is carried on, or forms part of, a flat spring 3| which is supported at one end On a block 33 on the front surface I of the chassis or base upon which the tuning element 1 is mounted.

The wedge-shaped detent-forming element 2'! lies adjacent the free end of the spring 3|. This free end of the spring 31 carries on its under side a Weight 35 and an arm or cam follower 31 which,

when pressed downwardly as by means of a cam 39 and suddenly released, imparts a force to the wedge shaped element 21 of an intensity sufficient to form a notch or detent 29 in the soft metal disc I5. The cam 39 for actuating the weighted detent-forming element 21 preferably has a gradual rise from the point A to the point B and a sudden dwell or drop from the point B to the point A. Thus, as it is rotated counterclockwise in contact with the cam follower 31, the weighted spring 3i is drawn away from the periphery of the disc l5 and suddenly released with a force sufficient to drive the wedge shaped element 21 into the relatively softer metal of which the index plate or disc I5 is constituted.

Since the notches or detents 29 are formed in situ, that is, without removing the disc l5 from the tuning control shaft 9, or otherwise disassembling the set, it is apparent that in setting up or indexing the unit, it is merely necessary to rotate the tuning control shaft 9 and the disc 15 thereon to that angular position whereat the station to be indexed is tuned in and, with the disc in that position, to actuate the detent forming element 21 by means of the knob 4| on the shaft 43 for the cam 39. Since the detent-forming element 21 is normally biased by the spring 3| against the periphery of the disc l5, the said element 2'1 serves as a pawl for the detents in said disc. Thus, when the tuning shaft 9 and the disc I5 thereon are later rotated to tune in a desired station, the pawl moves in and out of the detents individual to the other stations in the set up until the approximate setting of the de sired station is reached, whereupon the V-shaped element or pawl 21 engages the detent individual to that station and the operator is advised by his sense of touch that the exact setting for that station has been achieved.

Referring to Fig. 3, the shaft 3 to which the knob H, and cam 39 are attached may be mounted in a bushing 45 for both rotational and axial movement. The bushing Q5 has a spirally tapered end, with a drop or detent C in its taper, and the shaft 43 is provided with a pin ll which rides on this tapered end until it abuts the stop C, hence in order to project the cam follower 37 (see Fig. 2) over the drop BA of the cam 39, for indexing purposes, it is necessary to push the knob 41 inwardly against the force of a biasing spring 49 prior to rotating it. As shown .in Fig. 2 when it is desired to tune the set to an unindexed station the knob 41 may be partly rotated, say 180, to withdraw the wedge shaped element 21 away from the indexing disc i5.

In the embodiment of the invention shown in Figs. 4 and 5, the indexing disc, which is here designated 55 is immovably fixed to a supporting plate 5? at the rear of the control panel 59. The indexing or disc plate 55 is provided with an outwardly turned soft-metal rim r inwhich the notches or detents 6| individual to the stations are formed by means of a wedge-shaped element 63 carried on a spring 55 which is mounted on the main tuning shaft 61 adjacent the rear surface of the tuning control knob 69. The wedge-shaped detent forming element 63 is accessible from the front of the set through an orifice 'H which is provided for the purpose in the knob 69. Thus, in order to set up a station it is merely necessary to insert a punch (not shown) into the orifice, and with the leading end of the punch in contact with the outer surface of the wedge-shaped element 63 to deal the punch a thrust or blow of an intensity sufficient to deform the soft metal of which the rim r of the disc 55 is constituted.

As above indicated, and as in the previously described embodiment of the invention, the wedge-shaped detent forming element 63 is spring mounted and, during subsequent tuning operations comprises a pawl for the detents in the indexing disc or plate 55.

It is not to be inferred from the foregoing description that the invention is limited to installations wherein the indexing plate is employed in conjunction with a conventional condenser type of tuner, as it may readily be adapted to tuners of other types. Thus, referring to Fig. 6, the invention is shown as applied to a cord driven permeability'type tuning system wherein movement of a magnetic core 15 within a coil 11 provides the requisite changes in the electrical circuits essential to tuning. In this embodiment of the invention, the indexing mechanism is similar to that described in connection with the device of Figs. 1-3 with the exception that the indexing plate I9 is mounted on a stub shaft 8! (instead of on the main tuning shaft) and is provided with a pulley 83 for a cord drive comprising a driving cord 85, pulleys 87, 89 and a second cord 8! whose ends are connected to the opposite terminals of the magnetic core 75.

Other modifications of the invention will suggest themselves to those skilled in the art. It is to be understood therefore that the foregoing description of certain presently preferred embodiments of the invention is to be interpreted as illustrative and not in a limiting sense except as required by the prior art and by the spirit of the appended claims.

What is claimed is:

1. In combination, an instrument capable of various settings and comprising an indexing element constituted of an easily deformed material, and means mounted in operative relation with respect to said indexing element for generating and applying a deforming force thereto at points corresponding to selected ones of said settings.

2. The invention as set forth in claim 1 wherein the means for applying said deforming force to said indexing element comprises a spring actuated pawl.

3. In combination, radio apparatus having a tuning control shaft, an indexing element mounted in operative relation with respect to said control shaft, and a pawl for said indexing element mounted adjacent said element, of means mounted in operative relation with respect to said indexing element for generating and applying a force to said indexing element of an intensity sufiicient to form a detent for said pawl in said element at a point corresponding to the setting of the station to be tuned.

4. The invention as set forth in claim 3 and wherein said detent forming force is applied to said indexing element through said pawl.

5. In combination, radio apparatus comprising a control panel, a tuning control element mounted adjacent the front of said panel, a tuning control shaft controlled by said element, an indexing element mounted in operative relation with respect to said control shaft, and a pawl for said indexing element, of means accessible from the front of said control panel for forming a detent for said pawl in said indexing element at a point corresponding to the setting of a station to be tuned.

6. The invention set forth in claim 5 and wherein said tuning control element comprises an apertured knob and said detent-forming means is accessible through said aperture.

'7. In combination, an instrument capable of various settings and comprising an indexing element having a surface constituted of an easily deformed material, a pawl mounted adjacent 10 said indexing element and through which a deforming force may be applied to said surface at points corresponding to selected ones of said settings, means formally biasing said pawl into con tact with said surface, and means for moving said pawl against the force of its bias out of 15 said shaft.

WENDELL L. CARLSON. 

